“It’ll be hilarious, Ju-Ju,” the person who is now almost certainly Julia Roberts’ former agent presumably barked down a phone in LA 18-odd months ago. “It’s the story of Snow White, retooled for today’s modern sensibilities! You’ll play the Wicked Queen – but in a sexy, sassy way! She’s hot! She’s bad! This ain’t your grandmother’s reimagining of a classic fairytale!” And then they probably clicked their fingers in the air or something.

And you can see why Roberts would have thought it sounded like a hoot: who wouldn’t want to play one of the classic villains of children’s literature, perhaps inspiring new generations to rediscover the works of the Brothers Grimm? Maybe they sent her a script too, though one assumes with all the dialogue missing, and some clips of the films they were planning to rip scenes from. And that’s fine – I for one have spent many hours watching and re-watching Labyrinth and The Princess Bride, although I’m probably not going to be taken to court for remaking key scenes from them (the ballroom from the former, the rapier duel from the latter) as part of what is laughably called an original new work.

The problem with Mirror Mirror doesn’t lie with Roberts, though, who works with what little she’s given. Neither does it lie with former-model-now-It-girl-in-waiting Lily (daughter of Phil) Collins, whose main directive as the film’s lead was presumably to look as much as possible like Audrey Tatou in Amelie promotional stills. Nor can one blame male lead Armie Hammer, who shows an unexpected aptitude for broad physical comedy, especially if you know him only as the Winklevoss Twins in The Social Network. The problem is that the film looks like a video clip and has a script that reeks of a desperate, last-minute punch-up, apparently by writers hoping one day to graduate to adding pop-culture references to Family Guy.

After a genuinely artful animated opening montage setting up the story of Snow White – mother dies in childbirth, grief-stricken father raises her, falls in love with evil queen who he marries before vanishing conveniently in the woods – we’re in the palace with the Queen whaling on poor, poor Snow who – as the wise and noble servants explain – just has to learn to believe in herself, or something.

However, she evidently has no self-esteem issues that she needs her staff to help her overcome: no sooner has she slipped out the palace for a quick visit to the struggling commoners in the outside world than she undergoes an immediate blossoming of revolutionary spirit. Within minutes she’s plotting a coup with hunky prince Andrew Alcott (Hammer), recovering in the palace after being robbed and stripped by seven dwarvish bandits (all of whom are actually pretty good, to be honest – especially leader Grimm, played by Danny “Mickey from Seinfeld” Woodburn).

Queen orders Snow’s death, Snow meets dwarves, something something believes in herself unconvincing CG monster and we’re at the happy ending via a nice piece of stunt casting with Sean Bean as the returned king, cashing in on the success of Game of Thrones with a closing monologue that will go down in the annals of cinema history as among of the most moronic passages to be emitted from a human mouth. And then it’s time for the big Bollywood dance number, because of course it is.

The script doesn’t know if it wants to be a modern family classic, a zippy action adventure, a wry post-modern meta-fable or a heartwarming coming of age story, and so mixes up clunky dialogue, saccharine sentiment and elbow-in-the-ribs anachronism at every turn (“Isn’t this the Queen’s sled?” “No, it’s a rental” Boom!), and if that fails – which it consistently does – it’s over to the queen’s courtier Nathan Lane for a pratfall.

Director Tarsem Singh is best known for J-Lo’s gaudy, confused thriller The Cell and REM’s filmclip for ‘Losing My Religion’, and therefore seems an odd choice for making a whimsical family action-comedy. In any case, he manages to make the whole thing look both spectacularly expensive and incredibly cheap, intercutting boundless CG vistas with swooping Peter Jackson-ish helicopter shots into the live action sequences all obviously shot on a soundstage.

Julia Roberts’ former agent will remember Mirror Mirror as an important piece of cinema, since it’s what marked the boundary between their career as a powerful Hollywood player and their new life as a struggling temp with night terrors and a drinking problem, but fortunately the rest of us can avoid it as we would a poisoned apple. The actors give it a red hot go, but the script, the direction, the production design, the wacky references to focus groups… you know, one star seems at least three stars too many.